In the vacuum furnace art a workpiece is held within a heating element to receive heat therefrom for whatever purposes the workpiece is being heat treated, such as being sintered. It has been traditional in vacuum furnaces to hold the heat generated by the heat element within the heat chamber by virtue of a heat insulation wall. It has also been recognized in the prior art that when a workpiece has been heat treated and quenching, or cooling, is necessary, it behooves the system to provide a substantial amount of cooling gases rapidly to effect the cooling or quenching. In the prior art, the quenching has been accomplished by building the heat insulation wall with at least two removable sections. One such section is located at the bottom of the heat insulation wall and the other section is located at the top of the heat insulation wall. When quenching is to take place, the removable sections of the heat insulation wall are moved downward or sideways and inert gas is pumped into and through the heat chamber with such inert gases passing through the openings left by the removed wall sections. Such removable wall sections have very often been attached to a hydraulic device, or some other mechanically movable device, which acts to move a removable section of the wall to a new location within the vacuum furnace housing.
Such a prior art system has infirmities. In such prior art systems the hydraulic devices are mounted in the side wall of the vacuum furnace housing with one part of the hydraulic device being located inside of the vacuum furnace housing and the other part of the hydraulic device being located outside of the vacuum furnace housing. Therefore such a hydraulic device must be sealed to keep the ambient atmosphere from entering into the vacuum furnace chamber. It can be readily understood that if such a seal breaks the workpiece becomes oxidized and great damage can be done to the side walls of the vacuum furnace. Secondly such hydraulic devices, or mechanical devices (as do any mechanical systems), often fail with use because of normal wear. Thirdly the quenching operation in such a prior art system is relatively time consuming because of the time required to move the removable sections of the heat insulation wall. The present invention involves no moving parts and involves no parts which require a sealing technique to permit a member to be located part way in and part way out of a vacuum furnace housing. Yet the present invention provides a means for retaining the heat generated by the heating element within the heat chamber and permits rapid quenching of the workpiece.